Mass transit vehicles—such as passenger aircraft, boats, trains, subway cars, and buses—frequently include carpeting in the passenger compartment of the vehicle. This carpeting is exposed to a particularly harsh environment—high traffic, dirt, heavy equipment (e.g., beverage carts), spills, and the like. In passenger aircraft, the carpeting is also subjected to cyclical forces due to repeated changes in cabin air pressure that cause the cabin itself and its floor or deck structure to stretch and widen during expansion cycles and contract during compression cycles. These environmental and other conditions necessitate frequent replacement of worn, dirty or damaged carpeting.
In view of the above considerations, carpeting in mass transit vehicles should be engineered to the extent possible for wear resistance and ease of installation and removal. In addition, in passenger aircraft and maritime applications, the carpet needs to meet industry specifications for flame, smoke and toxicity. Moreover, in aircraft applications, because of the relationship between aircraft weight and fuel efficiency—and thus operating costs—it is preferable to minimize carpet weight while maintaining the other functional properties discussed above as well as esthetic requirements and objectives.
Broadloom carpet has traditionally been used in mass transit applications. The carpet is typically cut into appropriately-sized strips, the edges of the carpet strips are bound (“serged”) to prevent or minimize unraveling, the strips are positioned on the surface of the vehicle floor or deck, are further cut as necessary and are adhered to the floor or deck of the vehicle with adhesive. Broadloom carpet in these applications exhibits good strength and wear properties, but because the floor is carpeted with custom-cut strips sized to fit the vehicle, removal and replacement of damaged carpet sections is difficult and unnecessarily expensive, as damage to only one section of the strip can necessitate removal and replacement of the strip in its entirety. Moreover, in aircraft applications installation and replacement of broadloom carpet requires the carpet to be sized in the aircraft and removed for cutting, as cutting in-place could damage the skin of the aircraft.
In addition, in order to remove and replace the strips it is necessary to remove the seats and/or other equipment in the vehicle. In a passenger compartment of an aircraft, for example, replacement of a carpet strip can require the removal of several aircraft seats. Another drawback is that electronics mounted in the seats, e.g., audio connections and video screens, may also need to be removed or disconnected.
Carpet tiles can be an attractive choice for mass transit applications. Use of carpet tiles, which do not need to be serged, would simplify installation as compared to broadloom carpet. Carpet tiles can also allow for more efficient replacement of damaged carpet sections, since individual tiles can be replaced instead of entire strips of broadloom carpet. Another advantage of using carpet tile in aircraft applications is that if a tile needs to be cut it can be cut on a cutting board on the aircraft (unlike broadloom carpet).
Carpet tiles are generally produced and sold as squares. When non-square tiles are needed, the tiles are cut to the desired size. This is suitable for most commercial applications, but presents inefficiencies in mass transit applications. The floors of passenger aircraft have tracks that project from the floor and run most or all of the length of the passenger cabin to allow for installation of passenger seats of various sizes with various front-to-back seat separations and in various aircraft seating configurations. These tracks cannot be covered with carpet because they must remain accessible for attachment of seats. Although it may be possible for a seating configuration to be selected that utilizes tracks at equidistant lengths across the body, or breadth, of the aircraft, in almost all cases the seating configuration will require carpet to have several different widths in order to cover the entire breadth of the aircraft. When strips of broadloom carpet are utilized, strips are cut to match the widths between tracks, and the cut edges are usually bound. With conventional square carpet tiles, however, in order to cover the entire breadth of a passenger compartment, multiple tile sizes would be necessary for positioning in the different widths of gaps between the tracks without cutting tiles: e.g., if the aircraft requires four different broadloom strip carpet widths, then four different sized square carpet tile products would be required. Alternatively, larger tiles can be used by cutting them to the desired width, but this would be time consuming and wasteful.
In addition, carpet tiles—in any carpeting application—require good dimensional stability characteristics. Tiles should resist deformation and maintain their dimensions when subjected to varying temperatures, moistures, pressures, or other stresses. Among other things, carpet tiles that lack dimensional stability are more likely to buckle, or “dome” in the center of the tile and less likely to lie flat. Good dimensional stability characteristics are even more important in mass transit applications, where the tile is subjected to harsh environmental conditions as described above. Carpet tiles for use in passenger aircraft would also need to meet applicable specifications for flame, smoke and toxicity.
Current carpet tile technologies can produce carpet tiles having good dimensional stability and flame and smoke characteristics. Reissued U.S. Pat. No. Re. 34,951, incorporated herein by reference, describes one such carpet tile. Other prior art carpet tiles are described in U.S. Pat. Nos. 4,010,301, 4,010,302, 5,198,277, 5,204,155 and 5,560,972, the disclosures of which are incorporated herein by reference.
Each of these patents disclose carpet tiles that include a carpet pile embedded, tufted into or otherwise attached to a primary backing layer. These carpet tiles further include additional backing layers, which are formed from various materials and provide dimensional stability and strength to the carpet tile. Common backing layer materials include polyester, polyvinyl chloride, nonwoven glass fibers, and the like. In order to reduce the cost of backing, one or more fillers, such as calcium carbonate, are typically incorporated into the backing layer. These and most other conventional carpet tiles are relatively heavy, a not undesirable property because weight contributes to the ability of such tiles to lie flat and remain in place when installed.
While such conventional carpet tiles are suitable for many commercial and residential applications; they are not well adapted for applications in which light weight tile is desirable because they are relatively heavy, and this makes them less suitable for use in certain mass transit vehicles, particularly including passenger aircraft. Moreover, the broadloom carpet currently being used in mass transit vehicles, while perhaps lighter than conventional carpet tiles, have completely different dimensional stability characteristics that preclude the broadloom carpet from being cut into tiles and installed in the vehicle.